Previously, many approaches have been taken in endeavoring to provide an accurate means to measure the width of a sheared piece of material or the location of an angular brake. Prior art has been using back gauges for this purpose for some time and a search did not disclose any front gauges at all, however, back gauges may have some of the same elements if not the same utility. The following U.S. patents were at least considered related:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 4,033,572 Cailloux July 5, 1977 3,926,081 Roberts Dec. 16, 1975 3,314,322 Cutter, Jr. Apr. 18, 1967 3,176,559 Kootz Apr. 6, 1965 2,520,495 Dehn Aug. 29, 1950 ______________________________________
Cailloux teaches a pair of movable abutment arms on separate carriages along a rail acting as a common support. A pair of driving means with brakes are controlled from two boxes near the operator.
Roberts presents a safety warning system for use on a shear with a light beam and photosensor beneath the cutting blade to detect the stack-up of material sheared stock and warn the operator to prevent the back gauge from striking the stacked stock of material.
Cutter, Jr. discloses a gauge with a scale bar on the bed and a pin removably mounted on the bar. The pin is set at a distance from the bar or correspond to a hole previously punched. A hold down mechanism, also slideably mounted, engages the sheet in the region of the pin. Parts are sheared from a strip by engaging the hole of each piece in succession, or a guide bar is used to engage the edge of the strip.
Kootz uses an indexing device which prevents the droop inherent in the unsupported length of sheetmetal extending over the work edge with an inclined plane constraining the leading edge of the indexing member. A coupling allows the inclined plane member to fall out of the way as the workpiece is sheared.
Dehn takes advantage of a back gauge using a pair of vernier dials, one reading in fractions of the graduations of the other and both geared to the adjusting mechanism. The gauge setting is accomplished by rotating a hand crank which links a pair of stops operating in spaced relationship with each other.